439 
air, which I here subjoin, enabled me, by means of this ex- 
pression, to calculate 19 additional values of m. 
Series 2. 
No t t |t—t| p m ~ 
1 51 33'S |. 17°5 | 30°55] :0122 
2 a3 34°5 | 18°5 | 30°35} -0116 
3 52 34 18 30°21 | +0118 
4 51 33 18 30°05 | “0115 
5 52 33°4 | 18°6 | 29:75} -0108 
6 53 34°3 | 18°7 | 29°50} :0118 
7 56°5 | 35:8 | 20°7 | 29°70} °0112 
8 58 37 21 29°72 | :0110 
9 58:2 | 37 21°2. 29°77 | <O113 
10 58 37 21 30°03} °0114 
11 58 37 21 30°15} °0113 
12 59 37°5 | 21°5 | 30°25) °0112 
13 59 38 21 30°26 | °0117 
14 61 38°7 | 22°3 | 30°21; ‘0113 
15 58°3 | 37-7 | 20°6 | 30°35| ‘0117 
16 58 37°5 | 20°5 | 30-45| -0117 
17 56:3 | 36°5 | 19°8 | 30°30} :0117 
18 57°5 | 37 20°5 | 30°20; 0116 
19 57°5 | 37 20°5 | 30°15} -0116 
Mean. = ‘01150 
3. Lastly, if in the formula f” and f’ be known, so also 
7 Vi 
£ — x a . Butin 
the case of air saturated with humidity, by being passed 
through water, its temperature is its dew-point; so that this 
latter is easily and certainly known. Hence, if the tempera- 
ture of such air be raised, and a wet and dry thermometer 
be observed in it, we have ¢, ¢/ and ¢”; and can therefore, by 
the expression just given, calculate the value of m. The 
following table includes 24 distinct observations, from which 
the values of the coefficient given in the last column have 
been thus deduced: 
is m, for it is obviously equal to 
